In a cellular communications network, some or all of the cells may be divided into two or more sectors. For instance, FIG. 1 illustrates a cell 10 of a cellular communications network that is divided into three sectors 12-1, 12-2, and 12-3, which are generally referred to herein as sectors 12. Conventionally, a base station (e.g., a Node-B, an enhanced Node-B (eNB), or a Base Transceiver Station (BTS)) serving the cell 10 includes a separate amplifier and antenna for each of the sectors 12. The antennas are so-called sector antennas that radiate corresponding beams 14-1 through 14-3 that fill the corresponding sectors 12 with limited overlap into adjacent sectors 12. For the conventional base station, there is no power sharing between power amplifiers for the sectors 12 and, as such, the amplifier for each of the sectors 12 must be designed to satisfy maximum power level demands for the sector 12. In addition, if one of the power amplifiers or the corresponding transceiver fails, the downlink in the corresponding sector 12 is totally lost.
As one solution to the lack of power sharing, U.S. Pat. No. 7,206,355, entitled DIGITALLY CONVERTIBLE RADIO, and U.S. patent application Ser. No. 13/705,704, entitled DISTRIBUTED DIGITALLY CONVERTIBLE RADIO (DDCR), disclose embodiments of a Digitally Convertible Radio (DCR) and a Distributed Digitally Convertible Radio (DDCR), respectively. In one embodiment, the DCR or DDCR includes multiple parallel power amplifiers and enables power sharing between the power amplifiers such that any one of the power amplifiers is not required to be designed to satisfy maximum sector power level demands. The DCR and DDCR allow power sharing and connectivity for up to N radio transceivers and up to N antennas. An N×N Analog Hybrid Matrix (AHM) enables this functionality. In the DCR, the AHM is included within the DCR. Conversely, in the DDCR, the AHM is external to the DDCR in order to enable flexible use of radio units to, e.g., scale and share radio frequency (RF) power, scale the number of sectors, and/or scale capacity.
Additionally, in order to reduce capital and operating expenses, the number of components that must be installed on a tower or other structure should be limited. In some cases, the installation costs and ongoing site lease payments are dependent on the number of components installed. Also, additional components add complexity to the system and may necessitate additional safety precautions such as lightning protection. One way of addressing this problem is an Antenna Integrated Radio (AIR) unit, which is a product manufactured and sold by Ericsson. An AIR unit combines a radio unit and an antenna into an integrated unit. AIR units reduce the cost of installation by reducing the number of components to be installed, and lead to, for example, increased efficiency due to shared heat dissipation.
AIR units are typically single-sector solutions. For a multi-sector base station, multiple AIR units are typically installed in a multi-sector configuration. Each of these AIR units requires resources such as a power source and lightning protection on the power connections. Additionally, when there are low traffic conditions either upon initial deployment or at off-peak times, the single-sector AIR units offer little flexibility in terms of deployment cost and power savings. The DDCR discussed above allows for multi-sector flexible sharing of radio resources. However, implementing the DDCR concept when using multiple single-sector AIR units for a multi-sector base station is infeasible. The DDCR concept requires an external AHM, but the single-sector AIR units do not provide a common access point for the feeder cables for all three sector cables to be connected to the external AHM. As such, there is a need for an improved AIR unit that addresses these issues.